1. Field of the Invention
The present invention relates to an image processing method and an image processing apparatus for carrying out image processing on image data obtained by a digital camera. The present invention also relates to a program that causes a computer to execute the image processing method.
2. Description of the Related Art
An image obtained by photography with a digital electronic still camera (hereinafter referred to as a digital camera) can be recorded as digital image data in a recording medium such as an internal memory built in to the digital camera or an IC card. The image can then be displayed by using a printer or a monitor, based on the image data that have been recorded. In the case of printing an image obtained by a digital camera in the above manner, the image is expected to have as high a quality as a photograph printed from a negative film.
A digital camera comprises elements such as an optical system (a lens diaphragm, a shutter, a flash, and the like), an imaging system (such as CCDs and a signal processing unit), a control system (for AE, AWB, and AF), and a recording/reproducing system (for compression/decompression, memory control, and display). As factors affecting a quality of an image to be reproduced, color temperature of the flash, AE (Automatic Exposure) processing, AWB (Automatic White Balance) processing, a color filter for CCD color separation, the number of pixels, tone conversion, and a matrix operation for obtaining brightness/color difference signals can be listed, in addition to performance of the lens. In a digital camera, these factors are controlled to obtain image data that enable reproduction of a high-quality image.
Meanwhile, by using a printer or a monitor, a photographer himself/herself can freely print or display an image he/she photographed with a digital camera, without involving a DPE store. However, in order to obtain a print of sufficient quality, correction is necessary after printing or displaying image data. Consequently, this operation becomes considerably troublesome and inefficient if a large amount of prints are generated. For this reason, users wish to obtain high-quality prints by requesting printing of images obtained by digital cameras from DPE stores, as in the case of conventional prints generated from negative films.
However, the factors affecting the quality of are produced image varies, depending on a manufacturer or a model of a digital camera. Therefore, in order to reproduce a high-quality print, a DPE store needs to carry out printing while considering a characteristic of each digital camera of a specific model, since the DPE store generates prints from image data obtained by digital cameras of various models. For this reason, a system for obtaining a high-quality print has been proposed (Japanese Unexamined Patent Publication No. 11 (1999)-220687). In this system, the model of a digital camera is judged from tag information recorded by the digital camera, and image processing is carried out on image data by using an image processing condition that varies in accordance with the digital camera model. In this manner, a high-quality print can be obtained, regardless of a digital camera model.
In the system described above, at the time of carrying out the image processing on image data obtained by a digital camera, camera model information regarding the digital camera is obtained from the tag information accompanied by the image data, and the image processing condition appropriate for the model is read from a storage apparatus. The tag information includes not only the camera model information but also various kinds of information that is useful for image processing. However, the system described above carries out the image processing without sufficient use of the information. A method of setting the image processing condition that is obtained by the system based on statistic information of the image data is also described in Japanese Unexamined Patent Publication No. 11(1999)-220687. However, the image processing condition set according to the statistic information is a result of inference and not highly reliable.